Piston for internal-combustion engines



. J. PONDELICK.

`PISTON FOR INTERNAL COMBUSTION ENGINES Filed March 1'1, 1925 Patented Ier... il, i925.

uNrro sra` Jorim roNnnLroK, or RIVERSIDE, rLLrNors.

PISTON FOB INTERNAL-COMBSTION EGNES.

Application led March 11, 1925. Serial No. 14,590.

To all whom it may concern.'

4Be it known that I, JOHN PoNDnLIoig a citizen of the' United Sta-tes, and a resident` of Riverside, county of'Cook, Illinois, have invented certain new and useful Impro'vements in and for Pistons for Internal-Confl-A bustion Engines, of which the following is a specification. n

This invention relates to pistons forini 'ternal.combustionengines and more partie, ularly to pistons composed of aluminum o r an aluminum alloy, -and has for its main object to provide wearing surfaces for such pistons.

It is well known that aluminum and aluminum alloys are too soft and generally of insufficiently uniform density to be well adapted for the manufacture ofpistons for internal combustion engines unless equipped with wearingsurfaoes of a metal, preferably cast iron, which is well adapted to stand the wear and, by reason of the fact that-cylinders of suchk engines kare most Tgenerally 'made .of

cast-iron, have the same coeflicient of eX-A pansion as said cylinders. l

The object of the present invention is, therefore to provide a' composite piston consisting of a body of aluminum or an aluminum alloy and certain annular cast-iron wearing elements lpermanently associated with the aluminum or similar body in such manner as to permit free relative contrae tion and expansion of said wearing elements and' said body without, however, permitting orl occasioning any'looseness in the association of said parts such as might occasion leakage or rattling during piston reciprocations.

A further object of the invention i-s to so effect association of said body' and wearing elements as to obviate chipping or breakage of the latter under the influence of. `the strains and'stresses resulting from the dierence in coeflicients of expansion thereof.

vA further .object of the invention is to so construct or form the wearing elements as to cause the metal of' the body of the pis`- ton when cast about the said elements, to

flow into every crevice or hollow yofv the' latter to therebyeect uniformity of association of said body and said elements.

A further objectof-the invention lis to so4 form the wearingelements as to avoid delicate or easily fr acturable parts or projections for locking the same to the piston body and tovmake them of such length.(ax

ially of the piston) and proportionate thinness as'to permit the same to' yieldto eX- treme stresses due to overheating Vof the engine cylinders and thev like without fracturing. Y y

The preferred embodiment of the invention is illustrated .in the accompanying drawings, wherein :-r n v Fig. 1 is a central longitudinalV of a piston constructed in accordance with vthe invention.

Fig. 2 is a plan view ofa reinforcing member for the piston, constructed in accordance with the invention. n.

Figs. 3, 4 and 5 are radial Sections on thel lines 3-8, ll-4 andai-5, respectively, of Fig. 2.

The piston, which is of the usual trunk type used in internal combustion engines, consists of the cylindrical body 1 provided with an integral head 2 at one end and with bearings' 3 between its endsfor the sh tft or pin of the connecting rod (not shown).

' The inner projecting ends of vsaid bearings 3 are reinforced and supported by the integral radial ribs 4 extending in tapered formv from thehead 2 to said bearings.A

The piston is provided just below the head ,2 and above the bearings 3 with. a plurality of annular grooves-5 adapted to. receive ordinary piston rings.

Between said bearings 3 and the nearest '[The elements 6" and -7 are substantially identical in construction but may differ as to length (axially, of the piston). Hence a descrlption of one thereof will apply tol both. except as hereinafter particularly pointed out.

Each of said'elements 6 and 7 is composed, preferably, of castiron and comprises a ring having a' somewhat sphere-concave innerA surfaceS bordered by the annular flanges 9 having opposed concavely rounded vopposed surfaces which merge into the substantially sphere-concave inner face of-the ring. Or, in other words, the radius of curvature (axiallyof 'the ring) of the inner surface of the ringis reduced to provide llets where said surface merges into the inner surfaces of said anges 9.' This permits 'the moltenl aluminum to readily flow into and ll'everyff part of the'hollow surface of the ring.

The end surfaces of the ring are paralpresented by Ithe inner lel over that portion of-their areas indicated at lying next adjacent the outer surface of thesame. The portions of said .end i surfaces or faces lying inwardly of the por.- tions or areas 10 are dividedA into an equal numberv of relatively oppositcly tape-red or beveled areas 11 and 12,'respectively, the

areasll at one end of the ring being opposed tothe areas 11 of the other end, this being true also of the areas 12. Thus radial sections of the ring through an arcuate area `11 will, as shown 1n Fig. 4, present end surfaces which converge toward the axis of .the ring while similar sections through the areas 12 will, as'shown in Fig. 5, present surfaces which diverge toward the ring axis. Between the areas 11 and 12, there are formedv the rounded shoulders 13 which, by engagement with the similar shoulders formed in the body of the piston, prevent rotation of the rings relatively to the said body without, however, interfering .with the relative expansion' and'contraction of the latter relatively to the ringsG and 7 The parallel faces of the annular grooves 8' also permit such relative expansion and 'contraction.

Preferably ,only the ring 6 is provided at diam-etrically opposite points with the inwardly extending projections 13 which engagey at their extreme inner end portions inl .the ribs 4 if the latter are provided.

In casting therings 6 and 7, the outer body portions lying between the parallel end faces 11 thereof, are-rendered wide enough radially to provide excess metal for lgreater strength 'and rigidity in accurately machining the inner and end Vfaces thereof and also to permit the rings to be readil f supported in the mold into which the'alumr num body-metal is cast, the initial diameter of the latter being less than the extreme diameter of the said rings.` Preferably the outer surface of the ring lis machinedbe- 4fore the same is mounted in the mold to cut away some of the excess'metal and leave the two annular flanges 15. These are afterwards cut off as the outer surface of the ring ,is turned down to the -diameter indicated'by thel dotted lines 16.

Obviously the rings 6 and 7 `Will act similarly to chills in castiron molds and will canse a more rapid congelationof the aluminum immediately proximate thereto. Furthermore, the coefficient of expansion of the aluminum is Yi'ater than that of castiron so that in cooling, the aluminum will shrink away from the ring surfaces both radially and longitudinally of thefpiston During this shrinkage, the aluminum surfaces opposed to the surfaces 12 of the rings will moveinto snug contact with the latter and thus avoid' all loose association between vthe rings and the piston body. Uponv expansion vof the latter, both radially and longitudi` l tions of the rings are then turned down to' adiameter providing the usual running fit within the engine cylinder.y

The portions of the ring ends presenting the tapered surfaces 12 constitute arcuate flanges which possess great strength and are not easily broken away from the ring body. The cross-sectional dimensions of the latter are also so proportioned to 'length axially of and to -diameter of the ring as to render it suiciently iexible to accommodato itself to unusual strains'and stresses of an unequal or unbalanced nature Whlch .might result from differences in temperature at opposite sides of the piston or cylin'" der qr both or which ymay result from differences in density of the metal or cross-sectional Adimensions of the cylinder body .The body-inetal which fillsthe hollow. in the inner face of the ring will, when fully shrunk, be spaced from said face only to a 4Very inappreciable extent. The latter may be defined as being within the limits of fleX- ibility of the ring and thus affording opposed reinforcing elements which will prevent flexion of 'said rings to the point where there is danger of fracture thereof.

l claim as my invention:

1. In -a composite piston of the kind specified, wearing elements having end surface formations relatively arranged to constitute alternately oppositely disposed wedge formations.

2. In a composite piston of the hind sperified, wearing elements having end surface "formations presenting alternately oppositely disposed obstructions for engagement by vthe op osed similar surfaces of the bodymetal uring expansion and contraction rcspectively of the piston body. 3. In a compositepiston of the kind specified, wearing elements provided in their inner peripheral faces with annular substantially spher-concaye grooves merging into parallel annular edge-anges for permitting free relative expansion and contraction of said elements and the piston body without fitting metal for impartingal'fstrains or stresses upoir he Walle'.l

of saidgrooves while" effecting the j rojec-- `tion into said grooves of a. Wide rib o interpreventing excessive -fiexion of said elements.

4. Ina composi -ner peripheral faces Wlth annular substanimparting strains or stressesupon thejvallsl of said-grooves, the end surfaces'of sa1d-ele entire structure.y l 5. In a composite pistonjof the-kind speer' tially.. sphero-concave ro'oves 'merging 4into parallel annular edgeyanges for permitting saidelements and the piston body Without ments being divided into a'V-plu'rality of alternately oppositely beveled arcuate'portions to effect a wedging engagement with the bodyI metal upon a relative movement of said wearing elements and. piston bodyA in re'-4 'sponse to variations in temperature of the fied, wearing' elements provided in theirinner faces with substantiallysphero-concave annular grooves merging-into annular edgeflanges, and alternately oppositely disposed bevel formations at the ends of saldwearmg elements for effecting a Wedging engagement with the body metal upon a relative move-f ment of sa-id wearing elements andv piston body in response to variations in temperature of the -Whole structure.

6. In a composite piston of the kind speci-` fied, Wearing elements having end surfaces"yr 35 in positelybeveled, the beveled portions adaptart annularly parallel and inf part oped' to efect a Wedging engagement with the body metal upon a relative movement of te piston of the kind speciaf fied, wearing elements provided in their 1n response to variations `temperature ly oppositely beveled portions, the latter `response to variations in' temperature o v the 40 lvvhole structure. .l i x f p 7.1111 a composite piston of the kind specified,' wearing elements having` end suraces .in part annularl parallel and in. part alp-' ternatelyv bevele to constitute alternately l o posit'ely disposedA wedge formations"for] e ecti'ngza wedging engagement .wtlrtllel body* metal' u'p'on arelativejmovemet of,v said ywearir'lg elementsxand said Wearing elementsand' pistoribodi -vvhole structure. y

8. In a composite piston' of tliekind s ed, Wearing elements providedinltlieifin ner 'peripheral faces Y with 'substantiai sphro-concave annular grooves, the endsn.- ifaces of said elements-presentingfin parten'-l nular parallel areasa'l'idfiny art oppositely` beveled portions, the lattera, apted toelet a Wedging engagementfwith'the'body met upon a relative movement ofsaid wearing-.60 elements and piston body in responseytoty' variations irl-temperature of the 'Wholefstcturei-l 9. In a composite piston of the jkind pe ilied,` Wearing elements provided in their inj nerr 'peripheral faces -with substantially sphere-concavey annular grooves, the end sur-v faces of said elements presenting in part, 'annular parallel areas and in part alternateadapted to effect a wedging engagement with the bodymetal upon a relative move- 'ment of said Wearing elementsandpiston body in response to variations vin temperature of the whole structure. i n

' l j JOHN PONDELICK. 

